Requirements
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- Minindn (The demo was tested on mininet ver 2.2.1 and mini-ndn version 0.1.1)
Download minindn at https://github.com/named-data/mini-ndn
You can follow the instructions in the INSTALL.md of the minindn package that lists all the required packages on your machine. Typically, you need to have a working NDN environment, e.g., NFD, NLSR and some ndn utilities (in particular, ndnpoke and ndnpeek must be installed in the system to run successfully our illustrative test. Those utilities are part of the NDN essential tools package).

- P4 bmv2 a.k.a. P4 software-switch
You may avoid downloading and running a P4 compiler for the bmv2 target, because a compiled version in json format of the ndn_router.p4 source files is shipped with this software. However, you need to download and compile the P4 bmv2.
Download the bmv2 at https://github.com/p4lang/behavioral-model and follow instructions therein.

- crcmod library: a pure-Python implementation of CRC32C
The createFIBrules.py python script computes crc32 sums of names and name components. The instructions to install the library depend on your operating systems. On Debian-based OSes, the following steps should do the job:
$ sudo apt-get install gcc python-dev python-setuptools
$ sudo easy_install -U pip
$ sudo pip install -U crcmod


Changes to mini-ndn
-----------------------------------------
Follows a quick description of the changes and adds applied to the minindn installation. Further explanation of the patch files is included in a README within the subdir mini-ndn.

The nlsr is commented out and not launched at boot on the ndn nodes.

Some settings imported from the p4_mininet test environemnt are applied to the ndn hosts in file in ndn_host.py

Those changes are included as two different patch files in NDN.p4 The file 'mini-ndn.patch' must be applied to the main dir of mini-ndn. While the file ndn_dir.patch must be applied to the ndn directory. This can be done as follows:
cd $MININDN_DIR; patch -p1 < $NDNP4_DIR/mini-ndn/mini-ndn.patch
cd $MININDN_DIR; patch -p1 < $NDNP4_DIR/mini-ndn/ndn_dir.patch

Additional files to be included in mini-ndn
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The variable $MININDN_DIR is a placeholder for the mini-ndn home directory in your system.

- $MININDN_DIR/ndn/experiments/my_experiment.py : it describes a basic experiment to be run in the topology. The experiment consists of two nodes exchanging an Interest and a Data packet by using ndnpeek and ndnpoke application. The code is pretty easy to follow. It includes some set-up to be done for the first node, on which some routes need to be installed. Then, in the run method the ndnpeek and ndnpoke calls are instantiated on different host nodes.

- $MININDN_DIR/ndn/ndnP4_demo.py : this file is provided within the p4-lang repository by Barefoot Networks. It's not actually in use, but it has been included to track some code that has been leveraged in our mininet setup.

- $MININDN_DIR/ndn/p4_mininet.py : the template this file is based on is likely the bmv2/mininet/p4_mininet.py. However, it includes more things. First, there is a parseConfig method to read and parse the attributes specified in the p4-switch.conf. While in the original file, P4Switch's arguments were passed as parameters to the class constructor. Second, there is a method that fills the P4-switch's tables. Third, the original version of this file defined classes P4Host and P4Switch, now it defines only a custom version of P4Switch, since the ndn node class is used to instantiate hosts. 

- $MININDN_DIR/p4-switch.conf : it includes arguments that are usually passed to the switch executable as well as the path to the executable itself. The minindn bin script looks for this file in /usr/local/etc/mini-ndn/; so you must either copy the file in such directory or copy to a different directory and specify the absolute path of that directory through the "--p4-dir" optional argument.

P4 switch configuration file
-----------------------------------------
The "p4-switch.conf" file contains arguments loaded by the experiment at run-time that are used to tailor the p4-switch behavior. You MUST edit it in order to modify the paths to files on your file system. Every line contains a small comment after the semicolon explaining the field meaning.
You must either copy "p4-switch.conf" to "/usr/local/etc/mini-ndn/" or copy to a different directory and specify the absolute path of that directory through the "--p4-dir" optional argument.

IMPORTANT - MUST BE DONE: you must write the appropriate paths in your system for the following attributes: exe, cli, json, commands.


Experiment topology description
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The simple topology used for this experiment is described in the p4.ndn.basic.conf. It consists of two hosts running NFD and a switch connecting them which runs the ndn_router.p4 program.


Configuration file for NFD
----------------------------------------
The directory includes the configuration file used for the experiment, while it is not mandatory to use the same configuration file, it is recommended for people who don't know how to troubleshoot problems with the NFD. If there exists some configuration parameter which is not supported in your system, the NFD may crash and so the experiment fails.

Translate your own rule-set
---------------------------------------
Human-readable prefixes must be translated in p4-switch's rule by the createFIBrules.py script. As an example, we have included an incomplete "ndn_commands.partial.txt" rule-set that has all the forwarding plane rules except the FIB's ones. In addition to that, there is a bare simple illustrative file "fib.txt" that includes three rules (syntax: prefix output_interface). To convert those rules to commands that can be used to fill the p4-switch's FIB, you may proceed as follows:

python createFIBrules.py --fib fib.txt --cmd ndn_commands.partial.txt -c 5

The '-c' specifies what is the maximum number of name components the switch is able to parse in NDN packets. In our code this is a constant in the *.p4 files which is set to 5. If you want to change this value, you need to modify the source files and compile them again to generate a new json file to be loaded by the p4-switch.

The rules contained in fib.txt are translated into commands and appended to the ndn_commands.partial.txt. Then, this file has to be linked into the p4-switch.conf under the attribute "commands" as follows 

commands: $ABSOLUTE_PATH/ndn_commands.partial.txt ; Path to the control plane rules as to fill the switch's tables

Start the experiment
-----------------------------------------
1 - Generate ndn_router.json or copy the one provided with this software bundle in the directory specified in the p4-switch.conf.
2 - Write the right paths of tools and configuration files in your system
3 - Create the commands to fill the switch's tables as explained in the previous section "Translate your own rule-set"
4 - sudo minindn $MININDN/p4.ndn.basic.conf --experiment=P4_NDN_experiment --p4

Few seconds after the experiment is started, you are prompted to the mininet CLI. If the experiment was run successfully, you should have the content "Hello world" written in the file /tmp/a/packetPayload.txt. The text is the payload of the content object retrieved by node 'a' through the ndnpeek utility and provided by node 'b' through the ndnpoke utility.
You can check how NDN packets are processed by the p4 switch, which runs the ndn_router.p4 program, by looking at the log in 'p4s.s1.log'.

How to cite this work
-----------------------------------------
If you are referring to NDN.p4 in a published work, please cite the following paper, not just this github repository. Thank you!

Salvatore Signorello, Radu State, Jerome Francois, Olivier Festor, "NDN.p4: Programming Information-Centric Data-Planes", Proceedings of the IEEE International Workshop on Open-Source Software Networking at NetSoft2016, Jun 2016, Seoul, South Korea.